The safety selector in a common AR15-type semi-automatic firearm operates by rotation of a lever 90 degrees from a “safe” position to the “fire” position. In the “safe” position, an internal shaft of the selector blocks movement of a rearwardly extending portion of the trigger member. When rotated to the “fire” position, a flat or recessed portion of the shaft is positioned over the rearwardly extending portion of the trigger member, allowing actuating movement of the trigger. A spring biased detent pin engages detent notches with a connecting groove therebetween to limit rotation of the safety selector to 90 degrees and to provide certain positioning in the “fire” and “safe” positions. Although the standard AR15 safety selector has an actuation lever only on the left side of the firearm receiver, ambidextrous safety selectors have been provided, which attach a second actuation lever on an opposite end of the selector shaft to provide actuation from the right side of the receiver as well.
Adaptations have been made to safety selectors for AR15-type firearms, as well as other similarly operating firearms, so that there is only 45 degrees of rotation between the “safe” and “fire” positions. Although certain military requirements have specified a 45 degree selector, it has not been widely adopted in the field.
In order to convert the safety selector from one that operates with 90 degrees of rotation to one that operates with 45 degrees of operation, replacement of the safety selector part is required. Although the conversion can be accomplished by a person of minimal skill using minimal tools, a separate part has to be interchanged with the existing part to accomplish the conversion.